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1999 Feb. 26

    PIXY system new version is released.    

MISAO Project Announce Mail (Feb. 26, 1999)

Hello. I am Seiichi Yoshida working on the MISAO project.

The latest version of the PIXY system, an automatic astronomical image examination software, is released at the MISAO Project home page. The version is 1999 Feb. 17.


Some new functions are added in the new PIXY system, not only to examine your image comparing to star catalog like the GSC or the USNO-A1.0, but also to remove false estimation of magnitude by accumulating observation data of variable stars, or to discover new variable stars in the accumulated magnitude data, or to find true candidates of new objects among many noises or normal stars by checking past images. The Ageo Survey Team (KenIchi Kadota and Seiichi Yoshida) are actually using these functions and operating the survey work and variable stars observation automatically.

Documents on the system are also updated. Some new documents on the previous new functions are available at the new corner "Second Step" on the PIXY system home page. The "Second Step" corner has the following documents.

  • Identification Database Construction
  • Identification
  • Magnitude Report
  • Magnitude Database Construction
  • New Object Survey

These documents are available as the document package from the "Download" page.

*** Identification ***

You can identify detected stars by the PIXY system with known variable stars using -identify option of the PIXY system.

You have to construct the database of known variable stars (the identification database) in advance for identification. The web page "Identification Database Construction" describes the steps. The targets to identify with are as follows.

  • GCVS2000
    A comprehensive catalog of main variable stars all over the sky (34,760 stars).
    Modifications for the GCVS2000.
  • TmzV
    The list of new variable stars discovered by Kesao Takamizawa (230 stars on Feb. 17).
  • HadV
    The list of new variable stars discovered by Katsumi Haseda (9 stars on Feb. 17).
  • OGLE
    The catalog of long period or non periodic new variable stars discovered in the MACHOs survey.
  • Novae since 1995
    A list of novae since 1995 compiled from IAUCs
  • Supernovae since 1996
    A list of supernovae since 1996 compiled from IAUCs.
  • NSV
    New Catalogue of Suspected Variable Stars (14,811 stars).
    IRAS Point Source Catalog.
    IRAS Faint Source Catalog.
  • Markarian
    The catalog of galaxies with strong ultraviolet rays (1,525 stars).
  • Veron
    The catalog of quasars, active galaxy nuclei, BL Lac type objects, etc. (15,106 stars).
  • STM
    The list of candidates of "noise of plates" in the GSC, compiled by Minoru Sato (1,757 stars).
  • MCG
    A catalog of faint galaxies (29,003 stars).

These catalogs are available at the web page "Reference Catalogs":


After you added the catalogs into the identification database using the attached program in the PIXY system, you can find these objects in your images automatically.

Among these catalogs, the following ones are always updated.

  • TmzV
  • HadV
  • Novae since 1995
  • Supernovae since 1996

When you know some other catalogs available, please tell me by E-mail.

By the way, the NGC2000 (the catalog of 7,840 NGC objects and 5,386 IC objects) is also used for identification. However, the current program cannot read a file available from a WWW site.

*** Magnitude Report ***

You can create a magnitude report of detected stars using -report option of the PIXY system.

The format of the report is:

HT UMA  7.5     = GSC3452.1191 = IRAS 11455+4848
IRAS 11469+4842 <14.4
J114833.70+484313.1     13.5
GSC3452.1111    14.9
GSC3452.1127    15.6
GSC3452.1130    13.3
GSC3452.1162    12.0:
GSC3452.1256 + GSC3452.1259     12.3
GSC3452.1458 + GSC3452.1498     13.2    (NGC 3896, MCG+08-22-008)

You cannot send this report directly to some public society like the VSNET. This is because I do not known a proper format for the VSNET, etc. When you know the report format for a public society, please tell me by E-mail. I will modify the software to output the report in that format by -report option.

*** Magnitude Database Construction ***

Yon can accumulate the magnitude data estimated by the PIXY system of stars identified with known variable stars or the remarkable stars judged by the system into the database using -update option.

The advantages of accumulating magnitude data into the database are:

  1. You can judge a mistake of estimation.

    When the PIXY system output a wrong magnitude, you cannot judge it based on the result of one image. However, by accumulating magnitude data from many images into the database, you can see several magnitude of each star at one time. The magnitude value of a wrong estimation is evidently different from other magnitude data, so you can judge it as wrong estimation.

  2. You can discover errors in catalog or lack of catalog.

    The NC stars of the PIXY system (stars not detected but recorded in star catalog) may be errors in catalog. On the other hand, the ND stars (stars not recorded in star catalog) may be lack of star catalog. However, these stars may be just miss of detection, noises, mistake of identification, etc. You cannot judge it based on the result of one image. But by accumulating the magnitude data into the database, the true errors of catalog become always NC and only "not seed" data will be accumulated. The true stars lack of catalog become always ND and the same magnitude data will be accumulated.

  3. You can discover new variable stars.

    The PIXY system outputs the star whose estimated magnitude is much different from the value recorded in star catalog as a remarkable object, RM. The RM stars may be variable, but you cannot judge it based on the result of one image. By accumulating magnitude data into the database, many data of long period will be collected for each remarkable star, and you can judge if the star is really variable.

*** New Object Survey ***

You can search new objects automatically using -survey option of the PIXY system.

This function is special. It treats all images taken at one night together. You have to take two images of each area for this function. In addition, you had better have past images of the same area.

Before new objects survey, you have to examine all images by the PIXY system and create PXF files. You also have to identify with known variable stars, and register them into the magnitude database in advance.

Stars not recorded in star catalog, ND, output by the PIXY system are classified into the following four types.

  1. New objects
  2. Bright variable star
  3. Normal star not recorded in star catalog
  4. False detection

By identification with known variable stars, the "2. Bright variable star" can be rejected.

Then "4. False detection" are rejected. If there are two images of the same area at the almost same time, the real stars ("1. New objects" or "3. Normal star not recorded in star catalog") should be detected on both images at the same position as the same brightness. On the other hand, "4. False detection" will be rarely detected on both images at the same position as the same brightness. Therefore, the system investigates all images at one night and judged ND stars only detected from several images at the same position as the same brightness as real stars. It rejects other ND data only detected from one image as false detection.

Among the real stars, "1. New objects" will not be detected from the past images, but "3. Normal star not recorded in star catalog" will be detected on the past images at the same position as the same brightness. Therefore, the system also investigates past images and judges if the real stars are new objects or not.

After these processes, only candidates of new objects are remained.

Here I show you an example of new object survey result. The following example star is a candidate of new object discovered on survey images taken on Jan. 8, 1999. It was detected at R.A. 09h39m41s.63, Decl. +18o52'59".2 as 6.5 mag (the pixel size is 102.3 arcsec). It was detected from two images on the same night, so it must be a real star. The result shows that this star must be in the two images on Dec. 17, 1998, however it was not detected although the limiting magnitude is 9.0 mag.

1998 Dec 17.68730       <8.9R   19981217/35mm/0900+2000-R-01.mtf                (  79.47, 288.33)
1998 Dec 17.70119       <9.0R   19981217/35mm/1000+2000-R-01.mtf                ( 571.19, 321.71)
1999 Jan  8.76706       6.5R    19990108/35mm/0900+2000-R-01.mtf        ND-00001        (  52.82, 287.70)
1999 Jan  8.77731       6.5R    19990108/35mm/1000+2000-R-01.mtf        ND-00001        ( 564.02, 305.46)

The result contains the image file name and the (x,y) position of the star. By checking the images by myself, I confirmed a real star not found on the images on Dec. 17, 1998 is evidently found on the images on Jan. 8, 1999. However, I checked at the Minor Planet Checker:


and found that this star is a minor planet (4) Vesta.

The candidates of new objects discovered in the Ageo Survey are available at the MISAO Project home page. Any candidates are not real new objects, but I think you can see what kind of objects can be discovered by the PIXY system.


The past MISAO project announce mails are available at:


Seiichi Yoshida
Muraoka Lab., Waseda University, Japan

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